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Start Besu

Nodes can connect to Ethereum Mainnet and public testnets.

Use the besu command with the required command line options to start a node.

Prerequisites​

Besu installed

Local block data​

When connecting to a network other than the network previously connected to, you must either delete the local block data or use the --data-path option to specify a different data directory.

To delete the local block data, delete the database directory in the besu/build/distribution/besu-<version> directory.

Genesis configuration​

Besu specifies the genesis configuration, and sets the network ID and bootnodes when connecting to Hoodi, Sepolia, Ephemery, and Mainnet.

info

The following networks and testnets are deprecated: ETC Classic, Holesky, and Mordor.

When you specify --network=dev, Besu uses the development mode genesis configuration with a fixed low difficulty. A node started with --network=dev has an empty bootnodes list by default.

The genesis files defining the genesis configurations are in the Besu source files.

To define a genesis configuration, create a genesis file (for example, genesis.json) and specify the file using the --genesis-file option.

Syncing and storage​

By default, Besu syncs to the current state of the blockchain using snap sync in:

  • Networks specified using --network except for the dev development network.
  • Ethereum Mainnet.

We recommend using snap sync for a faster sync, by starting Besu with --sync-mode=SNAP.

By default, Besu stores data in the Bonsai Tries format.

Run a node for testing​

To run a node that mines blocks at a rate suitable for testing purposes:

besu --network=dev --miner-enabled --miner-coinbase=0xfe3b557e8fb62b89f4916b721be55ceb828dbd73 --rpc-http-cors-origins="all" --host-allowlist="*" --rpc-ws-enabled --rpc-http-enabled --data-path=/tmp/tmpDatdir

You can also use the following configuration file on the command line to start a node with the same options as above:

network="dev"
miner-enabled=true
miner-coinbase="0xfe3b557e8fb62b89f4916b721be55ceb828dbd73"
rpc-http-cors-origins=["all"]
host-allowlist=["*"]
rpc-ws-enabled=true
rpc-http-enabled=true
data-path="/tmp/tmpdata-path"
Warning

The following settings are a security risk in production environments:

Run a node on Hoodi testnet​

To run a node on Hoodi specifying a data directory:

besu --network=hoodi --data-path=<path>/<hoodidata-path>

Where <path> and <hoodidata-path> are the path and directory to save the Hoodi chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Sepolia testnet​

To run a node on Sepolia specifying a data directory:

besu --network=sepolia --data-path=<path>/<sepoliadata-path>

Where <path> and <sepoliadata-path> are the path and directory to save the Sepolia chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Ephemery testnet​

To run a node on Ephemery specifying a data directory:

besu --network=ephemery --data-path=<path>/<ephemery-data-path>

Where <path> and <ephemery-data-path> are the path and directory to save the Ephemery chain data to.

See the guide on connecting to a testnet for more information.

Run a node on Ethereum Mainnet​

To run a node on the Ethereum Mainnet:

besu

To run a node on Mainnet with the HTTP JSON-RPC service enabled and available for localhost only:

besu --rpc-http-enabled

See the guide on connecting to Mainnet for more information.

Confirm node is running​

If you started Besu with the --rpc-http-enabled option, use cURL to call JSON-RPC API methods to confirm the node is running.

  • eth_chainId returns the chain ID of the network.

    curl -X POST --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' localhost:8545/ -H "Content-Type: application/json"

  • eth_syncing returns the starting, current, and highest block.

    curl -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}' localhost:8545/ -H "Content-Type: application/json"

    For example, after connecting to Mainnet, eth_syncing will return something similar to:

    {
      "jsonrpc": "2.0",
      "id": 1,
      "result": {
        "startingBlock": "0x0",
        "currentBlock": "0x2d0",
        "highestBlock": "0x66c0"
      }
    }